Recurrence quantification analysis of eye movements during mental imagery.

Several studies demonstrated similarities of eye fixations during mental imagery and visual perception but-to our knowledge-the temporal characteristics of eye movements during imagery have not yet been considered in detail. To fill this gap, the same data is analyzed with conventional spatial techniques such as analysis of areas of interest (AOI), ScanMatch, and MultiMatch and with recurrence quantification analysis (RQA), a new way of analyzing gaze data by tracking re-fixations and their temporal dynamics. Participants viewed and afterwards imagined three different kinds of pictures (art, faces, and landscapes) while their eye movements were recorded. While fixation locations during imagery were related to those during perception, participants returned more often to areas they had previously looked at during imagery and their scan paths were more clustered and more repetitive when compared to visual perception. Furthermore, refixations of the same area occurred sooner after initial fixation during mental imagery. The results highlight not only content-driven spatial similarities between imagery and perception but also shed light on the processes of mental imagery maintenance and interindividual differences in these processes.